1. Field of the Invention
This invention relates to air conditioning systems and more particularly to such a system which is capable of severe duty operation in both ordinary and hazardous environments.
2. Description of the Related Art
Normal air conditioner systems are incapable of reliably operating in hazardous environments or environments that demand severe duty operation, particularly where there are wide variations in condensing air or water temperatures. Hazardous environments include those in which there is explosive gaseous material in the atmosphere which might explode in response to heat or a spark generated in the air conditioner systems. Severe duty conditions including widely variant ambient temperatures, high or low ambient temperatures, corrosive material, dust, dirt, humidity sea spray or other undesirable material in the atmosphere also present problems to the normal air conditioner which cannot handle the corrosive clogging or other undesirable effects of the material in the air and cannot handle high variations in ambient temperature. The components of a normal air conditioner also are subject to corrosion or other deterioration from such atmospheric material and this presents an additional problem.
A hazardous duty room air conditioner is described in U.S. Pat. No. 3,982,405 issued Sep. 28, 1976 to Siegler et al. In this patent, the generation of an arc is prevented by using sold state triacs in the switching circuits, contacts made of a metal such as gold which does not tend to arc and in which the switching devices are environmentally sealed. Measures are also provided to prevent frost collection on the evaporator coils during long periods of unattended use by means of a by pass valve connecting the output of the compressor to the input. This closes to connect the output of the compressor to the input when the suction pressure of the compressor goes below a predetermined normal level, thereby returning the evaporator to ambient room temperature to cause the frost to melt. The components of this air conditioner are made of durable material and coated with a corrosion resistant material. To prevent the co-mingling of outside air which may be polluted or contain dust or other undesirable material, a seal is provided between the outside atmosphere and the air within the air conditioner by employing a sealed unit in the portion of the conditioner surrounding the evaporator coils so that ambient outside air will not mix with the air within the conditioner. Water collected in the air conditioner is evaporated by means of a slinger wheel which slings such water onto the hot condenser coil.